/*-------------------------------------------------------------------------
 *
 *      EUC_JIS_2004, SHIFT_JIS_2004
 *
 * Copyright (c) 2007-2017, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/backend/utils/mb/conversion_procs/euc2004_sjis2004/euc2004_sjis2004.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"
#include "fmgr.h"
#include "mb/pg_wchar.h"

PG_MODULE_MAGIC;

PG_FUNCTION_INFO_V1(euc_jis_2004_to_shift_jis_2004);
PG_FUNCTION_INFO_V1(shift_jis_2004_to_euc_jis_2004);

static void euc_jis_20042shift_jis_2004(const unsigned char *euc, unsigned char *p, int len);
static void shift_jis_20042euc_jis_2004(const unsigned char *sjis, unsigned char *p, int len);

/* ----------
 * conv_proc(
 *        INTEGER,    -- source encoding id
 *        INTEGER,    -- destination encoding id
 *        CSTRING,    -- source string (null terminated C string)
 *        CSTRING,    -- destination string (null terminated C string)
 *        INTEGER        -- source string length
 * ) returns VOID;
 * ----------
 */

Datum
euc_jis_2004_to_shift_jis_2004(PG_FUNCTION_ARGS)
{
    unsigned char *src = (unsigned char *) PG_GETARG_CSTRING(2);
    unsigned char *dest = (unsigned char *) PG_GETARG_CSTRING(3);
    int            len = PG_GETARG_INT32(4);

    CHECK_ENCODING_CONVERSION_ARGS(PG_EUC_JIS_2004, PG_SHIFT_JIS_2004);

    euc_jis_20042shift_jis_2004(src, dest, len);

    PG_RETURN_VOID();
}

Datum
shift_jis_2004_to_euc_jis_2004(PG_FUNCTION_ARGS)
{
    unsigned char *src = (unsigned char *) PG_GETARG_CSTRING(2);
    unsigned char *dest = (unsigned char *) PG_GETARG_CSTRING(3);
    int            len = PG_GETARG_INT32(4);

    CHECK_ENCODING_CONVERSION_ARGS(PG_SHIFT_JIS_2004, PG_EUC_JIS_2004);

    shift_jis_20042euc_jis_2004(src, dest, len);

    PG_RETURN_VOID();
}

/*
 * EUC_JIS_2004 -> SHIFT_JIS_2004
 */
static void
euc_jis_20042shift_jis_2004(const unsigned char *euc, unsigned char *p, int len)
{// #lizard forgives
    int            c1,
                ku,
                ten;
    int            l;

    while (len > 0)
    {
        c1 = *euc;
        if (!IS_HIGHBIT_SET(c1))
        {
            /* ASCII */
            if (c1 == 0)
                report_invalid_encoding(PG_EUC_JIS_2004,
                                        (const char *) euc, len);
            *p++ = c1;
            euc++;
            len--;
            continue;
        }

        l = pg_encoding_verifymb(PG_EUC_JIS_2004, (const char *) euc, len);

        if (l < 0)
            report_invalid_encoding(PG_EUC_JIS_2004,
                                    (const char *) euc, len);

        if (c1 == SS2 && l == 2)    /* JIS X 0201 kana? */
        {
            *p++ = euc[1];
        }
        else if (c1 == SS3 && l == 3)    /* JIS X 0213 plane 2? */
        {
            ku = euc[1] - 0xa0;
            ten = euc[2] - 0xa0;

            switch (ku)
            {
                case 1:
                case 3:
                case 4:
                case 5:
                case 8:
                case 12:
                case 13:
                case 14:
                case 15:
                    *p++ = ((ku + 0x1df) >> 1) - (ku >> 3) * 3;
                    break;
                default:
                    if (ku >= 78 && ku <= 94)
                    {
                        *p++ = (ku + 0x19b) >> 1;
                    }
                    else
                        report_invalid_encoding(PG_EUC_JIS_2004,
                                                (const char *) euc, len);
            }

            if (ku % 2)
            {
                if (ten >= 1 && ten <= 63)
                    *p++ = ten + 0x3f;
                else if (ten >= 64 && ten <= 94)
                    *p++ = ten + 0x40;
                else
                    report_invalid_encoding(PG_EUC_JIS_2004,
                                            (const char *) euc, len);
            }
            else
                *p++ = ten + 0x9e;
        }

        else if (l == 2)        /* JIS X 0213 plane 1? */
        {
            ku = c1 - 0xa0;
            ten = euc[1] - 0xa0;

            if (ku >= 1 && ku <= 62)
                *p++ = (ku + 0x101) >> 1;
            else if (ku >= 63 && ku <= 94)
                *p++ = (ku + 0x181) >> 1;
            else
                report_invalid_encoding(PG_EUC_JIS_2004,
                                        (const char *) euc, len);

            if (ku % 2)
            {
                if (ten >= 1 && ten <= 63)
                    *p++ = ten + 0x3f;
                else if (ten >= 64 && ten <= 94)
                    *p++ = ten + 0x40;
                else
                    report_invalid_encoding(PG_EUC_JIS_2004,
                                            (const char *) euc, len);
            }
            else
                *p++ = ten + 0x9e;
        }
        else
            report_invalid_encoding(PG_EUC_JIS_2004,
                                    (const char *) euc, len);

        euc += l;
        len -= l;
    }
    *p = '\0';
}

/*
 * returns SHIFT_JIS_2004 "ku" code indicated by second byte
 * *ku = 0: "ku" = even
 * *ku = 1: "ku" = odd
 */
static int
get_ten(int b, int *ku)
{
    int            ten;

    if (b >= 0x40 && b <= 0x7e)
    {
        ten = b - 0x3f;
        *ku = 1;
    }
    else if (b >= 0x80 && b <= 0x9e)
    {
        ten = b - 0x40;
        *ku = 1;
    }
    else if (b >= 0x9f && b <= 0xfc)
    {
        ten = b - 0x9e;
        *ku = 0;
    }
    else
    {
        ten = -1;                /* error */
        *ku = 0;                /* keep compiler quiet */
    }
    return ten;
}

/*
 * SHIFT_JIS_2004 ---> EUC_JIS_2004
 */

static void
shift_jis_20042euc_jis_2004(const unsigned char *sjis, unsigned char *p, int len)
{// #lizard forgives
    int            c1;
    int            ku,
                ten,
                kubun;
    int            plane;
    int            l;

    while (len > 0)
    {
        c1 = *sjis;

        if (!IS_HIGHBIT_SET(c1))
        {
            /* ASCII */
            if (c1 == 0)
                report_invalid_encoding(PG_SHIFT_JIS_2004,
                                        (const char *) sjis, len);
            *p++ = c1;
            sjis++;
            len--;
            continue;
        }

        l = pg_encoding_verifymb(PG_SHIFT_JIS_2004, (const char *) sjis, len);

        if (l < 0 || l > len)
            report_invalid_encoding(PG_SHIFT_JIS_2004,
                                    (const char *) sjis, len);

        if (c1 >= 0xa1 && c1 <= 0xdf && l == 1)
        {
            /* JIS X0201 (1 byte kana) */
            *p++ = SS2;
            *p++ = c1;
        }
        else if (l == 2)
        {
            int            c2 = sjis[1];

            plane = 1;
            ku = 1;
            ten = 1;

            /*
             * JIS X 0213
             */
            if (c1 >= 0x81 && c1 <= 0x9f)    /* plane 1 1ku-62ku */
            {
                ku = (c1 << 1) - 0x100;
                ten = get_ten(c2, &kubun);
                if (ten < 0)
                    report_invalid_encoding(PG_SHIFT_JIS_2004,
                                            (const char *) sjis, len);
                ku -= kubun;
            }
            else if (c1 >= 0xe0 && c1 <= 0xef)    /* plane 1 62ku-94ku */
            {
                ku = (c1 << 1) - 0x180;
                ten = get_ten(c2, &kubun);
                if (ten < 0)
                    report_invalid_encoding(PG_SHIFT_JIS_2004,

                                            (const char *) sjis, len);
                ku -= kubun;
            }
            else if (c1 >= 0xf0 && c1 <= 0xf3)    /* plane 2
                                                 * 1,3,4,5,8,12,13,14,15 ku */
            {
                plane = 2;
                ten = get_ten(c2, &kubun);
                if (ten < 0)
                    report_invalid_encoding(PG_SHIFT_JIS_2004,
                                            (const char *) sjis, len);
                switch (c1)
                {
                    case 0xf0:
                        ku = kubun == 0 ? 8 : 1;
                        break;
                    case 0xf1:
                        ku = kubun == 0 ? 4 : 3;
                        break;
                    case 0xf2:
                        ku = kubun == 0 ? 12 : 5;
                        break;
                    default:
                        ku = kubun == 0 ? 14 : 13;
                        break;
                }
            }
            else if (c1 >= 0xf4 && c1 <= 0xfc)    /* plane 2 78-94ku */
            {
                plane = 2;
                ten = get_ten(c2, &kubun);
                if (ten < 0)
                    report_invalid_encoding(PG_SHIFT_JIS_2004,
                                            (const char *) sjis, len);
                if (c1 == 0xf4 && kubun == 1)
                    ku = 15;
                else
                    ku = (c1 << 1) - 0x19a - kubun;
            }
            else
                report_invalid_encoding(PG_SHIFT_JIS_2004,
                                        (const char *) sjis, len);

            if (plane == 2)
                *p++ = SS3;

            *p++ = ku + 0xa0;
            *p++ = ten + 0xa0;
        }
        sjis += l;
        len -= l;
    }
    *p = '\0';
}
